全文获取类型
收费全文 | 227篇 |
免费 | 24篇 |
专业分类
林业 | 25篇 |
农学 | 13篇 |
50篇 | |
综合类 | 12篇 |
农作物 | 23篇 |
水产渔业 | 37篇 |
畜牧兽医 | 67篇 |
园艺 | 5篇 |
植物保护 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 19篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 14篇 |
2007年 | 9篇 |
2006年 | 8篇 |
2005年 | 9篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有251条查询结果,搜索用时 718 毫秒
91.
Teerapong Jaichansukkit Thanathip Suwanasopee Skorn Koonawootrittriron Padet Tummaruk Mauricio A. Elzo 《Tropical animal health and production》2017,49(3):503-508
The aim of this study was to determine the effects of daily ranges and maximum ambient temperatures, and other risk factors on reproductive failure of Landrace (L) and Yorkshire (Y) sows under an open-house system in Thailand. Daily ambient temperatures were added to information on 35,579 litters from 5929 L sows and 1057 Y sows from three commercial herds. The average daily temperature ranges (ADT) and the average daily maximum temperatures (PEAK) in three gestation periods from the 35th day of gestation to parturition were classified. The considered reproductive failure traits were the occurrences of mummified fetuses (MM), stillborn piglets (STB), and piglet death losses (PDL) and an indicator trait for number of piglets born alive below the population mean (LBA). A multiple logistic regression model included farrowing herd-year-season (HYS), breed group of sow (BG), parity group (PAR), number of total piglets born (NTB), ADT1, ADT2, ADT3, PEAK1, PEAK2, and PEAK3 as fixed effects, while random effects were animal, repeated observations, and residual. Yorkshire sows had a higher occurrence of LBA than L sows (P?=?0.01). The second to fifth parities sows had lower reproductive failures than other parities. The NTB regression coefficients of log-odds were positive (P?<?0.01) for all traits. Narrower ranges of ADT3 increased the occurrence of MM, STB, and PDL (P?<?0.01), while higher PEAK3 increased the occurrence of MM, STB, PDL, and LBA (P?<?0.001). To reduce the risk of reproductive failures, particularly late in gestation, producers would need to closely monitor their temperature management strategies. 相似文献
92.
93.
Role of sex steroids in gonadal differentiation of the mussel Choromytilus chorus (Bivalvia Mytilidae) (Molina 1782) 下载免费PDF全文
Maryori Ruiz‐Velásquez Manuel Zapata María Teresa Gonzalez Mauricio Escalona Maritza Fajardo Eduardo Tarifeño Juan Morales 《Aquaculture Research》2018,49(1):404-414
In Chile, the species Choromytilus chorus stands out for its ecological and economic importance. This mussel has a very particular condition in the colour of the gonad, being cream‐yellow colour the male gonad and dark brown the female which is hardly desired by the consumers. In this context, the aim of this research is to determine the role that sex steroids have in gonadal differentiation of the mussel C. chorus. For this, juveniles with sizes 15–22 mm were selected, which were subjected to acute exposure in the form of bath for 60 days to four treatments: T1: dihydrotestosterone (DHT); T2: 17β‐estradiol (E2), T3: fadrozole (F) and T4: DHT‐F (DF), plus a control without chemicals. Each treatment as well as control included three replicates with 90 individuals each. The mussels undergoing treatment with E2 had a sex ratio (male:female) of 0.47 compared to 1:1 in the control group. In contrast, in the groups treated with DHT, F and DF the sex ratio changed to 2.0, 1.60 and 1.70 respectively. In the fertilization trials, all the mussels produced functional gametes, as they were able to generate gametes that were developed to morula, and veliger larva. Nevertheless, it should be noted that the size of oocytes from the group exposed to estradiol (61.12 ± 2.40 μm) was significantly higher than in other groups. These results support the hypothesis that sex steroids would be involved in sexual differentiation of marine bivalves. 相似文献
94.
95.
Elisabetta Gotor Mauricio R. Bellon Muhabbat Turdieva Karim Baymetov Parhod Nazarov Elena Dorohova-Shreder Vladislav Arzumanov Mikhail Dzavakyants Abduvahob Abdurasulov Galina Chernova Eugeniy Butkov Francesco Caracciolo 《Agroforestry Systems》2018,92(5):1253-1266
The aim of this paper is to analyze the impact of a set of interventions related to on-farm/in situ conservation and use of fruit species (cultivated and wild) on farmers’ livelihoods and species diversity in Central Asia. Specifically, a difference-in-differences propensity score matching is used to evaluate the outcome of a development research program in Uzbekistan between 2005 and 2010. Species crop diversity maintained by farmers before and after the project increased as a result of the interventions, showing the efficacy of the interventions promoted by the projects in terms of conservation. Furthermore, innovations provided by the program increased both household propensity of marketing and self-consumption of target fruit. However, the program’s interventions did not seem to impact significantly any of the indicators related to household livelihoods. The short time elapsed between the end of the project and the impact assessment may be too brief to capture any observable impact on livelihoods. 相似文献
96.
在龙竹竹杆的3个不同高度取材加工成竹条,并浸泡在蒸馏水中,记录竹条的老化时间,分析龙竹条的抗弯机械性能。对于未加工的竹条,抗弯性能并不随着秆高而变化。相对于未老化的标本,老化的标本的断裂模数降低,并且从秆底部到秆上部减少。同时,通过对未老化标本和老化标本的比较,老化标本的抗弯模数也呈下降趋势,但对于取自同一部位且浸泡时间相同的标本而言,抗弯模数没有变化。利用光学显微技术和数字图象处理技术对杆不同部位的微观结构的变化进行评估。利用镶嵌技术分析横切面,这能够测量大量纤维的数量。结果表明,从数据来讲,在杆的各个高度,主要结构参数(如单位面积的纤维数量)无变化。然而,不同部位的纤维形态有所不同,在杆上部可发现更长的纤维。可用热解重量分析法确定龙竹的热性能。热降解过程中在单阶段发生,并于280.10C开始。在此过程中,可获得166KJ/mol的活化能。 相似文献
97.
Eva Guillamón Ana García-Lafuente Miguel Lozano Matilde D´Arrigo Mauricio A. Rostagno Ana Villares José Alfredo Martínez 《Fitoterapia》2010
Edible mushrooms are a valuable source of nutrients and bioactive compounds in addition to a growing appeal for humans by their flavors and culinary features. Recently, they have become increasingly attractive as functional foods for their potential beneficial effects on human health. Hence, food industry is especially interested in cultivated and wild edible mushrooms. 相似文献
98.
Semi-arid adapted nitrogen fixing trees of the genus Prosopis have been extensively used in Argentina for soil improvement, luxury quality lumber production and sweet (35% sucrose) pods for humans and livestock. Due to the great demand of Prosopis alba for lumber, erect, tall, high pod producing trees of this species have been greatly overharvested, leading to erosion of the gene pool. A previous progeny trial with 57 half sib families identified 12 trees with promise for rapid growth, high production of pods and sweet pods. This trial, on a site with a salinity of 8.6 dS m−1 EC and a pH of 7.7, examined clones of these 12 trees in a randomized complete block trial with 8 single tree replications for height, basal diameter, canopy height and diameter, production of pods, sensory characteristics of the pods, disease resistance and insect resistance. In the 5th year of production and 7th year from planting, three clones produced more than 50 kg pods per tree versus 32 kg for check. At this 10 m × 10 m spacing, this yield of 5000 kg/ha compares favorably to many other semi-arid crops, especially given the unfavorable salinity and pH. In contrast to genetic improvement in pod production, the clones had lower diameter, height and canopy growth than the check. The lower biomass production may be due to fibrous root system produced from cuttings, since some of the clones blew over in high winds but none of the checks produced from seed blew over. Companion seed orchards of salt tolerant clones may provide rootstock for these high pod production clones. Significant differences in insect and disease resistance of the clones were observed and full sib crosses were made to study the genetics of the resistance. All clones had good sensory properties for use in human food. This is the first replicated trial with multipurpose clones useful for lumber and human food. The annual diameter growth rates ranged from 2.8 to 4.1 cm year−1 which was estimated to produce an internal return of approximately 20% from lumber alone. 相似文献
99.
María Blanco Javier Fraguas Carmen G. Sotelo Ricardo I. Pérez-Martín José Antonio Vázquez 《Marine drugs》2015,13(6):3287-3308
This study illustrates the optimisation of the experimental conditions of three sequential steps for chondroitin sulphate (CS) recovery from three cartilaginous materials of Scyliorhinus canicula by-products. Optimum conditions of temperature and pH were first obtained for alcalase proteolysis of head cartilage (58 °C/pH 8.5/0.1% (v/w)/10 h of hydrolysis). Then, similar optimal conditions were observed for skeletons and fin materials. Enzymatic hydrolysates were subsequently treated with a combination of alkaline hydroalcoholic saline solutions in order to improve the protein hydrolysis and the selective precipitation of CS. Ranges of 0.53–0.64 M (NaOH) and 1.14–1.20 volumes (EtOH) were the levels for optimal chemical treatment depending on the cartilage origin. Finally, selective purification and concentration of CS and protein elimination of samples obtained from chemical treatment, was assessed by a combination of ultrafiltration and diafiltration (UF-DF) techniques at 30 kDa. 相似文献
100.
Amorim TM Macedo LL Uchoa AF Oliveira AS Pitanga JC Macedo FP Santos EA de Sales MP 《Journal of agricultural and food chemistry》2008,56(17):7738-7745
The digestive system of P. interpunctella was characterized during its larval development to determine possible targets for the action of proteinaceous enzyme inhibitors and chitin-binding proteins. High proteolytic activities using azocasein at pH 9.5 as substrate were found. These specific enzymatic activities (AU/mg protein) showed an increase in the homogenate of third instar larvae, and when analyzed by individual larvae (AU/gut), the increase was in sixth instar larvae. Zymograms showed two bands corresponding to those enzymatic activities, which were inhibited by TLCK and SBTI, indicating that the larvae mainly used serine proteinases at pH 9.5 in their digestive process. The presence of a peritrophic membrane in the larvae was confirmed by chemical testing and light microscopy. In a bioassay, P. interpunctella was not susceptible to the soybean trypsin inhibitor, which did not affect larval mass and mortality, likely due to the weak association with its target digestive enzyme. EvV (Erythrina velutina vicilin), when added to the diet, affected mortality (LD50 0.23%) and larval mass (ED50 0.27%). This effect was associated with EvV-binding to the peritrophic membrane, as seen by immunolocalization. EvV was susceptible to gut enzymes and after the digestion process, released an immunoreactive fragment that was bound to the peritrophic matrix, which probably was responsible for the action of EvV. 相似文献